Previous Year Question
What is the difference between Bluetooth and Wi-Fi devices?
Bluetooth uses 2.4 GHz radio frequency band, whereas Wi-Fi can use 2.4 GHz or 5 GHz frequency band.
Bluetooth is used for Wireless Local Area Networks (WLAN) only, whereas Wi-Fi is used for Wireless Wide Area Networks (WWAN) only.
When information is transmitted between two devices using Bluetooth technology, the devices have to be in the line of sight of each other, but when Wi-Fi technology is used the devices need not be in the line of sight of each other.
The statements (a) and (b) given above are correct in this context.
Correct Answer: A
Detailed Solution
Option (a) is correct. Bluetooth operates in the 2.4 GHz ISM (Industrial, Scientific and Medical) band. Its operating frequency range is approximately 2400–2483.5 MHz. In the context of the 2011 question, Wi-Fi could use the 2.4 GHz and 5 GHz frequency bands.
Option (b) is incorrect. Bluetooth is mainly used for short-range device-to-device communication and Personal Area Network (PAN)/piconet arrangements. In contrast, IEEE 802.11-based Wi-Fi is a Wireless Local Area Network (WLAN) technology. Therefore, describing Bluetooth as WLAN-only and Wi-Fi as WWAN-only is incorrect.
Option (c) is incorrect. Bluetooth uses radio waves; therefore, the communicating devices do not normally need to be in direct line of sight of each other. Wi-Fi likewise does not require direct line of sight for ordinary communication.
Current status: Wi-Fi is no longer limited to only the 2.4 GHz and 5 GHz bands. Newer IEEE 802.11 standards also operate in the 6 GHz band. Thus, (a) remains the correct answer in the context of the 2011 question, while the present-day Wi-Fi spectrum also includes 6 GHz.